Electromagnetic relay and free armature therefor

ABSTRACT

Free armature for electromagnetic micro-contact systems in the form of a blade having one end freely rolling on a pole member, and opposite sides spaced a predetermined distance from the rolling end and engageable with one or two contact members upon energization of an associated electromagnet, to complete a circuit between the armature and contact member.

United States Patent [1 K snee e1 ELECTROMAGNETIC RELAY AND FREE ARMATURE THEREFOR [75] Inventors: Peter Kupec; Ulf Rauterberg, both of Munich, Germany [73] Assignee: Siemens Aktiengesellschaft, Berlin,

Munich, Germany 221 Filed: Mar. 21, 1973 21 Appl. No.: 343,190

[30] Foreign Application Priority Data Mar. 22, 1972 Germany 2213970 Mar. 22, 1972 Germany...; 2213936 [52] U.S.Ci 335/196, 335/81,335/203 [51] Int. Cl. ..H01h 1/16 [58] Field ofSeai-ch 335/82,81,56, 200, 203, 335/196, 83

[56] References Cited UNITED STATES PATENTS 2,830,152 4/1958 Tasker et a1. 335/82 2,965,733 12/1960 Borg et a1. 335/81 3,529,268 9/1970 Rauterherg 335/56 3,731,240 5/1973 Meyer 335/200 Primary ExaminerHarold Broome Attorney, Agent, or FirmHill, Gross,Simpson, Van Santen, Steadman, Chiara & Simpson [57] ABSTRACT Free armature for electromagnetic micro-contact systems in the form of a blade having one end freely rolling on a pole member, and opposite sides spaced at predetermined distance from the rolling end and engageable with one or two contact members upon energization of an associated electromagnet, to complete a circuit between the armature and contact member.

12 Claims, 6 Drawing Figures PATENTEDum 22 m4 WEEK 2 0F 2 Fig. A

ELECTROMAGNETIC RELAY AND FREE ARMATURE THEREFOR FIELD OF THE INVENTION Mini-relay in hermetically sealed switching chamber, in which the armature is in the form of a blade mounted in the chamber without a rigid bearing, to roll upon its pole member to engage one or the other of two contact members.

BACKGROUND, SUMMARY AND ADVANTAGES OF INVENTION Mini-relays and particularly those having an armature forming a contact member and movable upon the energization of an electromagnet to open or close a circuit, in which the relay is in a hermetically sealed switching chamber, customarily insert the armature in the switching chamber without a rigid bearing, to rockingly move on a pole member, and to be maintained in a selected contact position by the attractional forces of the electromagnet. This arrangement has no fixed pivotal axis to absorb impacts during .the individual switching movements, which may occur by the tendency of the armature to recoil from its pole piece. With such switching arrangements in which the armature is 'maintained in position by the magnetic retaining forces of electromagnets, it has been difficult to provide a nonshiftable rolling point for the armature except by the frictional engagement of the armature with a surface about which it rolls. As soon as the impact forces exceed the magnetic and frictional retaining forces, the rolling pivotal axis of the armature slides in one direction or another.

The point of rolling contact of the armature with its contact surface has a tendency to be shifted both parallel and perpendicular to its ideal path, which shifting of the armature rolling contact point is extremely harmful in the operation of the relay. This is particularly due to the strong fluctuation of the reaction values, due to high wear and due to unsafe or uneven contacting or even complete failure to make a contact. In addition, with hermetically sealed mini-relays, the armature must center itself in its desired preselected position and stabilize itself there.

The German Offenlegungsschrift 1,922,204 discloses a possible method for eliminating shifting'of the annature parallel to the line about which it rolls by suitably shaping the pole surfaces. This, however, does not eliminate shifting perpendicular tothe rolling line of the armature in a direction toward the pole surfaces.

The German Offenlegungsschrift 1,614,943 attempts to stabilize the rolling-off line of the armature by providing a knife edge for the armature and mounting this knife edge in a corresponding recess in the pole member. This expedient, however, not only causes an increased wear at the rolling point of the armature, but also does not stabilize the armature in a direction parallel to its axis of rolling movement.

Such magnetic relay systems with bearing-free armatures have the drawback that movement of the armature is not braked by a reset spring. The armature thus hits the opposite pole pieces at a high rate of speed, which causes strong impacts and a high rate of wear and interferes with the stability of the armature positions.

A possibility of correcting shifting of the armature perpendicular to its rolling axis is by inclination of the engaging surfaces of the two pole pieces of the electromagnets and so spacing the engaging or contact surfaces of the pole pieces, that the armature contacts with the contact surfaces with a surface or line contact, depending upon whether equal or different radii are selected for the contact surfaces of the pole pieces, and the rolling contact surface of the armature. This arrangement makes it necessary to position the rolling axis exactly in the symmetry plane between the contact surfaces of the two pole pieces. In such an arrangement, possible shifting of the armature may be cor,- rected by the magnetic attraction forces which draw the contact surfaces of the armature into engagement with either of the pole pieces. With such a system, even very small deviations from the desired contact positions with the pole pieces, and deviations in the angle of inclination of the armature as well as the armature thickness tends to cause a sliding movement of the rolling axis of the armature as the contact is made, in order that the armature may rest upon the pole piece surface. Such sliding movements of the armature are undesirable, due particularly to the increased wear of the armature.

The present invention is thus based on a free rolling armature so rolling on its pole piece and located with respect to the contact surfaces that the armature centers itself relative to the contact surfaces without requiring a great deal of precision manufacture during production of the relay, and will always stabilize itself with a minimum amount of wear on the rolling axis of the armature even where the armature may shift perpendicular to the plane of the rolling axis of the annature.

This is obtained by fixing the contact areas between the armature and the opposite pole members at an ideal height with respect to the rolling axis of the armature, by means of convex protrusions provided on the contact surfaces of the pole pieces or the armature. The ideal impact level, therefore, is at a level where the recoiling impact is transmitted to the center of rolling movement of the armature to avoid the impact forces from affecting the point of rolling movement of the armature.

With such an arrangement, transmitting the impact forces at the correct distance from the rolling axis of the armature, shifting of the rolling axis of the armature is prevented at the instant of impact. Thus, an impact in the ideal impact level will always be obtained when the armature has reached its desired contact position and correcting forces will always occur at the rolling axis of the armature as the armature is shifted from its center position between its two contacts.

The convex protrusions may either be on the adjacent ends of the pole pieces or on opposite sides of the armature. The end of the armature rolling on its pole piece and free to move transversely along its pole piece will result in line contact between the annature and the selected pole piece with which contact is made. If the armature should not assume its desiredposition between the pole pieces prior to energization of either electromagnet or due to an impact on the relay, the contact lines between the armature and the opposite pole pieces are not positioned in the ideal impact level. The armature impact upon engaging its contact, however, causes sliding movement of the armature which ment are that the wear at the rolling contact line of the armature is extremely small and is practically zero when the deviations of the impact level of the armature with its pole pieces are so small compared with the ideal-impact level that the forces tending to cause deviation are canceled by friction.

With a plate or rod-type ofi armature, the ideal impact level is approximately two-thirds of the length of the armature extending along the pole piece from the rolling surface to contact point of the armature.

A further advantage of the present invention is that an electromagnet system with bearing-free armature is provided in which all the aforementioneddisadvantages and drawbacks, in particular the recoil effect during the impact, are reduced to as far a degree as possible by the provision of an armature that is at least .partially elastic. The armature will thus be temporarily deformed during the impacting process and can thereby absorb kinetic energy and store it in the form of potential energy. The instantaneous forces during the impacting process are, therefore, weakened and the impulse transmission is slowed down. Such an elastic armature bends through during the impact upon the opposite I pole members and hereby rubs against the contact surfaces and simultaneously converts a part of the kinetic energy into friction heat.

An armature bent into a U-shaped form with the closed end of the armature rolling about a pole member and the legs of the armaturebeing in the nature-of spring fork ends is a particularly advantageous armature for carrying out the principles of the present invention. With such an armature, one end serves as a contact end while the second end may freely oscillate. Such an armature mayhave relatively long springy legs and may have convex protrusionsfor engaging surfaces, protruding from its legs to enable the thickness of the legs of the armature to be maintained uniform throughout their length, and to thereby cause no increase in the armature mass.

The closed end of such an armature then will roll on a pole member, and one of two free legs will respectively impact upon. an opposite pole member while the second leg will follow in free oscillation. This slows down the impulse transmission and the first armature leg will make good contact with little, if any, recoil. If the armature legs furthermore extend close to each other, they can touch each other while impacting upon an opposite contact member, and thus convert further kinetic energy into friction heat.

In addition, and as a further development and advantage of the invention, the armature and the opposite pole members are wettened with a conductive liquid suchasmercury. This attains an additional damping of therecoiL. Where the armature may be U-shaped, the inner surfaces of the legs can also be wettened by mercury, sothat the mercury between the legs will addi- .tionally. dampen the armature oscillations.

Other objects, features and advantages of the invention will be readily apparent from the following description of several preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.

DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are diagrammatic views showing the pole members in section and illustrating the effects of different impact levels of the armature rolling about a base pole member.

FIG. 3 is a view illustrating an armature having a convex base and two opposed pole members having arcuate protrusions arranged at the ideal impact level of the armature with the protrusions.

7 FIG. 4 is a diagrammatic view illustrating two opposed pole members having inclined contact surfaces and showing protrusions extending from opposite sides of the armature'for engagingthese contact surfaces at the ideal impact level.

. FIG. 5 is a view like FIG. 4, but showing a U-shaped armature having convex protrusions extending from the legs of the armature for engaging contact surfaces of the pole members; and

FIG. 6 is a relay constructed in accordance with the principles of the invention utilizing a U-shaped armature with contact protrusions extending from each leg thereof.

DESCRIPTION OF PREFERRED FORMS OF INVENTION In FIG. 1' of the drawings, we have shown an armature 1 having a convex engaging or rolling end la rolling about a pole member 2 and selectively engaging opposite inclined contact faces of pole members 3 and 4 upon back and forth switching movements of the annature, caused by energization of either of the pole members by electromagnetic coils (not shown) in a manner well-known to those skilled in the art. The convex end laof the armature l is capable of sliding movement along the pole member 2 caused by impact forces as the armature makes its contact with either one of the pole members. As previously mentioned in the background of the invention, shifting of the armature perpendicular to its rolling axis is caused by outer shocks on the switch, and by impacts of the armature as it impacts the contact surfaces of either pole member 3 or 4. During such impacts, both a translational and rotary impact are transferred to the armature. If the point of impact is close to a free end 1b of the armature, as shown in FIG. 1, a rotary impulse will prevail at the rollingend 1a of the armature and the line of rolling movement of the armature will slide in the direction of the arrow 5 toward the pole member 4.

If, however, the impact force is close to the center of mass of the armature l as illustrated in FIG. 2, the linear impulse onthe armature will cause the line of rolling movement of the armature to move in the direction of the arrow 6. The armature 1 will then tend to hit the pole member 3 at the wrong impact level during the next switching movement and a steady shifting of the armature while passing its symmetry axis will result, which will tend to continue to move the armature toward an ofi-center position. It should be understood that this'wrong impact level occurs due to even minor inexactness in production of the switch either as to the height of the opposite. pole members or the angles of inclination of the contact faces of the pole members.

In FIG. 3 of the drawings, we have shown the effects of stabilizing a rolling armature. The armature 1 rolls on the pole member 2 on its convex contact surface 1a to carry out switching movements between spaced pole members 3 and 4. In this form of the invention, the pole members 3 and 4 are provided with arcuate protrusions 3a and 4a oppositely arranged, to effect impact to the armature along an ideal impact level indicated by the dash-dot line 7 when its rolling contact line is positioned in a symmetry plane between two protrusions or pole faces 3a and 4a.

Where the armature may not be in its true symmetry plane between the two pole members 3 and 4, a minor sliding movement may occur in the direction of the arrows 8 and 9 which has the effect of moving the rolling point of the armature into a centered position with respect to the pole faces during continued operation of the switch.

It should here be understood that the impact forces are reduced, the closer the armature is toward its centered or symmetry position, which places the impact points closer to the ideal impact points. As soon as the armature is centered in the symmetry plane between the opposite pole members, practically no shifting of the rolling axis of the armature will occur.

A further embodiment of the invention is illustrated in FIG. 4. In this form of the invention, the armature 1 has a convex rolling end 1a bearing freely on the pole member 2 and moving back and forth between the opposite pole members 3 and 4 due to the energization of a selected electromagnet (not shown), one being associated with each pole member. The pole members 3 and 4 extend in straight lines parallel to the pole member 2 and have facing depending inclined end portions 3d and 4d extending parallel to the longitudinal center of the armature when in either of its contact positions. The armature 1 has arcuate protrusions 1c on opposite sides thereof having substantially line contact with the contact faces 3d or 4d and cooperating with said contact faces to center the armature in its symmetry plane between the opposite pole members 3 and 4.

FIG. shows a U-shaped armature 1 which rolls upon a pole member 2 on its closed end 1a, and alternately contacts inclined contact faces 3d and 4d of two opposite pole members 3 and 4. The legs of the armature 1 have recesses 10 in the inner sides thereof at approximately two-thirds of the length of the armature, from the rolling end surface 1a, so that the impact upon the opposite pole members 3 and 4 will always be at approximately the ideal impact level of the armature. The base or rolling end 1a of the armature is furthermore bent at as large a radius as possible, to produce as great a contact surface as possible between the armature 1 and pole member 2.

The armature may be springy or elastic not only due to the selection of the material, but also due to its shaping and cross-section dimension, so that each time the armature leg 1b impacts upon an opposite contact surface 3d or 4d of a pole member 3 or 4, the second annature leg 1b can oscillate and thus weaken the impact. Simultaneously, the oscillatingly following second armature leg lb may touch the first impacting armature leg, giving both armature legs frictional contact, and converting a part of the kinetic energy into heat.

Thus, instantaneous forces produced during the impact will be essentially lowered compared with a massive armature, and the first impacting armature leg 1b will attain a substantially recoil-free electric contact with the contact surfaces 3d or 4d with the respective opposite pole members 3 or 4.

In the form of the invention shown in FIG. 6, a complete electromagnetic relay is diagrammatically shown, having an armature 11 rolling about an upright end 12a of a pole member 12, to carry out switching movements between contact surfaces 13a or 14a of respective opposite pole members 13 and 14 depending upon the polarization of energization of an electromagnetic coil 18. A switching chamber 15 contains the armature 11 and contact surfaces 13a and 14a of the pole members 13 and 14 and is hermetically sealed by a glass sealing member 16 totally enclosing said chamber. The pole members 12, 13 and 14, aside from serving as magnetic flux guidance elements, also serve as electric contacting elements.

A permanent magnet 17 is provided between the pole members 12 and 13 for maintaining a contact between aprotrusion 11c and the contact surface 13a or 14a. The magnet coil 18 extends about the pole member 14 and the inturned end of a flux guidance member 19, and is energizable to move the armature 11 to engage a protrusion 11c thereof with or to disengage the protrusion from a contact surface 14a of the pole member 14.

In one switching position of the switch, the magnetic flux of the permanent magnet 17 will proceed through the pole member 13, the flux guidance member 19, the opposite pole member 14, the armature 11 and the pole member 12. In the other switching position the annature 11 will close the circuit between the pole member 12 and pole member 13.

Therefore, energization of the electromagnetic coil 18 at one polarization will move the armature 11 to close a circuit between the pole members 12 and 14. Energization of the electromagnetic coil 18 at an opposite polarization will close a circuit between the pole members 12 and 13.

Referring now in particular to the U-shaped armature 11, the base of the U of the armature is rounded as indicated by reference numeral 110 and has rolling engagement with the upstanding end 12a of the pole member 12. The legs of the armature are bent or embossed outwardly adjacent outer ends 11b thereof, to provide arcuate protrusions 1 1c in the ideal impact area of the armature at a distance of approximately two-thirds of the entire length of the armature. This form of armature gives the required contact surfaces without increasing the mass of the armature and due to the U shape of the armature, the impact force on one leg is not transmitted to the impact force on the opposite parallel leg. Moreover, this armature has very little mass and is maintained in the respective rest positions onlyby magnetic forces and is independent of position.

An additional damping of the armature recoil may be attained by wetting the contact surfaces of the pole members 12, 13 and 14 within the switching chamber 15 as well as the entire surface of the armature with a conductive liquid such as mercury. Inparticular, the mercury positioned in the inner space 11d betweenthe two armature legs 11b will result in a good additional damping of the armature oscillations.

The U-shaped armature described herein. has many advantages. The armature, however, neednot necessarily be limited to a special U-shape or to. any other shape shown and described and in addition may be of any shape which can roll about a support and contact surface and have resilient properties and may even be a freely flying armature in an elastic embodiment.

We claim as our invention:

1. In an electromagnetic relay,

a free elongated magnetic armature serving as a magnetic and electric bridging element and having a convex freely rolling end and opposite contact surfaces spaced along said armature from said rolling end, a pole member having a plane engaging surface engaged by said rolling end of said armature and forming a base therefor and-directing the magnetic fiow toward and along said armature,

twospaced opposite pole members spaced from said first-mentioned pole member and adapted to be alternately contacted by the contact surfaces of said armature,

said opposite pole members having contact surfaces spaced from said first-mentioned pole member and located at an ideal impact level with respect to the rolling point of engagement of said armature with said first pole member, and the points of engagement between said armature and pole members being in the form of convex protrusions assuring the contact of said armature along the ideal impact level between said armature and pole members.

2. The electromagnetic relay of claim 1, in which the convex protrusions are formed along the contact surfaces of the opposite pole members.

3. The electromagnetic relay of claim 1, in which the convex protrusions extend along opposite sides of the armature and are in alignment with each other.

4. The electromagnetic relay of claim 3, in which the convex protrusions have engaging connection with said pole members at substantially two-thirds of the entire length of said armature.

. 8 a 5. The electromagnetic relay of claim 1, in which the armature is at least partially elastic and carries out switching operations along the elastic portion thereof.

6. The electromagnetic relay of claim 1, in which the armature is U-shaped in form and has a convex base and parallel legs extending therefrom, wherein the base has engagement with said first pole member, and electrical energizable means are provided forrolling said armature about said base from one pole member to the other.

7. The electromagnetic relay of claim 6, wherein the legs of the armature have aligned convex protrusions formed integrally therewith. I

8. The electromagnetic relay of claim 7, wherein the first pole member has an upright leg engaged by said convex base of said armature, the second pole member has an inclined contact face engaging one convex protrusion, the second pole member has a contact face extending perpendicular to said base, engageable with the other protrusion, wherein a permanent magnet maintains said armature in engagement with a contact face of either pole member, and an electromagnet is provided for moving said armature into contact engagement with the plane contact face of either pole member dependent upon the polarization of energization of said electromagnet.

9. The electromagnetic relay of claim 1, in which the armature is split along its free end to provide two springy fork-like ends.

' 10. The electromagnetic relay according to claim 1, characterized in that the armature and opposite pole members are wetted with a conductive liquid.

11. The electromagnetic relay of claim 10, wherein the armature is U-shaped in form and has oppositely facing aligned convex protrusions, and wherein the armature and opposite pole members are wetted with a conductive liquid.

12. The electromagnetic relay of claim 11-, wherein the conductive liquid is mercury. 

1. In an electromagnetic relay, a free elongated magnetic armature serving as a magnetic and electric bridging element and having a convex freely rolling end and opposite contact surfaces spaced along said armature from said rolling end, a pole member having a plane engaging surface engaged by said rolling end of said armature and forming a base therefor and directing the magnetic flow toward and along said armature, two spaced opposite pole members spaced from said firstmentioned pole member and adapted to be alternately contacted by the contact surfaces of said armature, said opposite pole members having contact surfaces spaced from said first-mentioned pole member and located at an ideal impact level with respect to the rolling point of engagement of said armature with said first pole member, and the points of engagement between said armature and pole members being in the form of convex protrusions assuring the contact of said armature along the ideal impact level between said armature and pole members.
 2. The electromagnetic relay of claim 1, in which the convex protrusions are formed along the contact surfaces of the opposite pole members.
 3. The electromagnetic relay of claim 1, in which the convex protrusions extend along opposite sides of the armature and are in alignment with each other.
 4. The electromagnetic relay of claim 3, in which the convex protrusions have engaging connection with said pole members at substantially two-thirds of the entire length of said armature.
 5. The electromagnetic relay of claim 1, in which the armature is at least partially elastic and carries out switching operations along the elastic portion thereof.
 6. The electromagnetic relay of claim 1, in which the armature is U-shaped in form and has a convex base and parallel legs extending therefrom, wherein the base has engagement with said first pole member, and electrical energizable means are provided for rolling said armature about said base from one pole member to the other.
 7. The electromagnetic relay of claim 6, wherein the legs of the armature have aligned convex protrusions formed integrally therewith.
 8. The electromagnetic relay of claim 7, wherein the first pole member has an uprigHt leg engaged by said convex base of said armature, the second pole member has an inclined contact face engaging one convex protrusion, the second pole member has a contact face extending perpendicular to said base, engageable with the other protrusion, wherein a permanent magnet maintains said armature in engagement with a contact face of either pole member, and an electromagnet is provided for moving said armature into contact engagement with the plane contact face of either pole member dependent upon the polarization of energization of said electromagnet.
 9. The electromagnetic relay of claim 1, in which the armature is split along its free end to provide two springy fork-like ends.
 10. The electromagnetic relay according to claim 1, characterized in that the armature and opposite pole members are wetted with a conductive liquid.
 11. The electromagnetic relay of claim 10, wherein the armature is U-shaped in form and has oppositely facing aligned convex protrusions, and wherein the armature and opposite pole members are wetted with a conductive liquid.
 12. The electromagnetic relay of claim 11, wherein the conductive liquid is mercury. 